You could ask: "If he has all the answers, why did it lose half its value since last July?"
What lost half of its value was the Rogers Commodities Index, not Roger's personal fortune which is kept private.
An explanation is in order for the Rogers Commodities Index. I read Rogers' books. He explained that when he decided to invest in commodities, he looked for a benchmark to represent commodity prices, and did not find a suitable one, so he made up his own. For example, he observed that rice has been a major staples around the world, but not adequately represented in the existing indices.
A drop of commodity prices would cause the Roger Index, in fact any commodity index, to drop. If Jim Rogers was able to tell in 2007 that the world recession would impact demand and got out of commodities, and now is getting back in, we do not know.
I do know that Jim is bullish on commodity demand for the long term, as the industrialization of China will be the driving factor. That is a highly plausible story, in my view. Keep an eye on the Chinese economy. When it resumes its boom, the commodity exporters in other countries will be rolling in dough. Same with the dry bulk shippers.